EFFECTS OF SONIC VIBRATION ON THE NUMBERS OF MICROORGANISMS CULTIVABLE FROM HUMAN SALIVA

¹ Department of Microbiology, School of Dentistry, University of Pennsylvania, Philadelphia, Pa.

1. A comparison of the numbers of colonies appearing on a blood agar medium after exposing separate aliquots of pooled saliva to sonic vibration (9,000 cycles per second, power output about 50 watts) and to a mechanical shaking method, indicates that significantly higher counts were consistently obtained after sonic vibration. It is likely that these differences are due to a more homogeneous dispersion of bacteria after sonic vibration.

2. The effects of sonic vibration on the counts may be noted as early as after 2 minutes of exposure, but the highest counts seem to be obtained after about 10 minutes. After reaching a maximum the counts become lower as the time of exposure is increased.

3. Similar effects may be noted on the numbers of colonies of streptococci and lactobacilli when aliquots from the sample are inoculated on separate media.

4. The possible use of sonic vibration, or some similar method for studying quantitative relationships between bacteria cultivable from saliva is suggested.

5. Various phases in the future study of the effects of sonic vibration on samples of saliva are discussed.